The invention relates to the use of an extract of Cimicifuga racemosa for treating estrogen-dependent tumors.
Extracts of the rhizome of the black cohosh (Cimicifugae racemosae rhizoma) exhibit estrogen-like effects. Components which bind specifically to estrogen receptors and are able to lower gonadotropin levels in ovariectomized rats have been found in the extracts. It has therefore proved to be of value to administer these extracts for the purpose of treating climacteric complaints and dysmenorrhea.
The use of estrogen-containing pharmaceuticals for regulating climacteric complaints is out of the question in the case of patients who are at risk of mammary carcinoma since the growth of estrogen-dependent tumors is naturally augmented by administering estrogen. Since the mechanism by which estrogen-analogous substances act is still unclear, a risk of estrogen-dependent tumors has, as a precaution, been regarded as a contraindication in regard to administering these substances.
It has been reported (Nesselhut et al. in TW Gynakologie (1993) pages 249 to 250) that relatively low concentrations of the plant drugs rhaponticin and Cimicifuga extract augment the proliferation of carcinoma cells in vitro.
It is also known to treat estrogen-dependent tumors with an antiestrogenic active compound. The currently most popular active compound of this type is tamoxifen (Z)-2-[4-(1,2-diphenyl-1-butenyl)phenoxy]-N,N-dimethyl-ethylamine.
For the above mentioned reasons, it was not possible to consider using estrogens or estrogen-analogous substances to regulate the climacteric complaints of the patients who were being treated with an antiestrogen of this nature.
Whether or not the proliferation of mammary tumor cells is inhibited depends on the concentration of the tamoxifen. However, it is not possible to increase the concentration to a range at which proliferation of the tumor cells is reliably prevented, since tamoxifen becomes toxic at these concentrations.
The present invention therefore takes, as its starting point, the problem of achieving tumor therapy even when using relatively low concentrations of anti-estrogen.